Filter element

ABSTRACT

The invention pertains to a filter element ( 1 ) that can be easily adapted to the respective filtration task and in which the risk of the catalytically active components separating from the filter is largely eliminated. The filter element consists of a dimensionally stable porous formed body ( 3 ), the interior of which is partially filled with a catalyst material ( 8 ) or a material ( 8 ′) that is coated with catalyst material such that a flow channel ( 10 ) remains open. It is possible to insert a perforated formed body insert ( 7, 7′, 7 ″) that causes the flow channel to remain open. The intermediate space between the formed body ( 3 ) and the formed body insert ( 7, 7′, 7″ ) is filled with a bulk catalyst material ( 8 ) or a bulk material ( 8 ′) that is coated with catalyst material.

The invention pertains to a filter element according to the preamble ofclaim 1.

The reduction of nitrogen oxides in gases is carried out in solidcatalysts by means of a selective reaction between the nitrogen oxidesand the reduction agents. Correspondingly high gas temperatures arerequired in order to achieve a sufficiently high catalytic activity andto prevent saline deposits from forming on the catalyst surfaces becausethis would lead to a, deactivation of the catalyst. For example,reduction catalysts for the cleaning of flue gases in power plants areused at temperatures of approximately 300° C.-350° C. in the flue gasflow between the boiler and the air preheater.

The ceramic catalyst material usually consists of rigid plates orhoneycomb elements, but may also be present in the form of bulk materiallayers.

In the so-called low-dust method, an electrostatic hot gas filter forlargely separating the dust is arranged upstream of the honeycombelements or plate catalysts. In the so-called high-dust method, the gaspasses the reactor filled with a catalyst without prior dedusting. Inthis case, the individual catalyst elements need to containcorrespondingly large flow channels for the gas in order to preventclogging.

In all aforementioned variations, other voluminous and complexapparatuses for the separation of nitrogen oxide need to be provided inaddition to the already existing apparatuses and devices for theprecipitation of other pollutant components. Such a complicated gascleaning technique is particularly disadvantageous when onlycomparatively small gas quantities need to be treated.

Consequently, DE 36 34 360 proposes to mix the gases containing nitrogenoxide with the reduction agent and to convey the mixture through atleast one catalytically active filter element that consists of a ceramiccarrier material and the catalytically active substances. Thecatalytically active filter element is also used for dedusting the gasescontaining nitrogen oxide. The filter element consists of felts orfleeces that are manufactured from fibers of the ceramic carriermaterial by means of compaction and doped with the catalytically activesubstances. The filter element may also consist of porous sinteredelements that are manufactured by sintering granules of the ceramiccarrier material and doping the carrier material with the catalyticallyactive substances. The filter element may have the shape of a filtercandle. The doping of the ceramic carrier material with thecatalytically active substances is realized by applying these substancesonto the ceramic carrier material before, during or after themanufacture of the felts, fleeces or sintered elements. This may, forexample, be realized by impregnating the filter elements with a salinesolution and subsequently heating the salt-doped filter elements.

DE 37 05 793 describes a filter device for cleaning gases whichcomprises a single tubular element of a heat-resistant expanded ceramicmaterial that simultaneously acts as a dust filter and, with acorresponding coating, as a catalyst.

EP 0 470 659 describes a method for separating dust and organiccompounds from gases that contain oxygen, in particular, combustiongases. In this case, the exhaust gas to be cleaned is conveyed throughat least one catalytically active filter element that is composed of aceramic carrier material and the catalytically active substances. Thefilter element may consist of a porous sintered element that ismanufactured by sintering granules of the ceramic carrier material anddoped with the catalytically active substances.

WO 9012950 describes a filter for diesel exhaust particulates whichconsists of honeycomb elements, wherein the first honeycomb elements areprovided with a first surface layer and conventionally cause a catalyticconversion of nitrogen oxides and carbon monoxide into nitrogen andcarbon dioxide, respectively. In this case, the second honeycombelements are provided with a second surface layer and catalyticallycause a reduction in the ignition temperature of the exhaustparticulates adhering thereon.

WO 9803249 discloses a hot gas cleaning device in the form of the filtercandle. On the outside, the filter candle is provided with a membranelayer of ultra-fine silicone carbide particles in order to filter outdust particles. A catalytically active layer of sintered siliconecarbide powder is arranged on the inside thereof viewed in the flowdirection. The catalyst consists of a vanadium-titanium compound, withwhich the silicone carbide filter is impregnated. The filter candle ismanufactured by subsequently coating a porous element. This has thedisadvantage that the porous layer cannot be uniformly applied such thatthe catalyst material is not homogenously distributed. Another problemcan be seen in the adhesion of the applied layer on the silicone carbideparticles. This problem becomes even more significant due to the factthat temperature fluctuations occur in the region of the hot gasfiltration which could promote a separation of the coating from thesilicon carbide particles.

Consequently, the invention is based on the objective of makingavailable a filter element that can be easily adapted to the respectivefiltration task and in which the risk of the catalytically activecomponents separating from the filter is largely eliminated.

This objective is attained with a filter element according to claim 1.

The filter element is characterized by the fact that the interior of aformed body is partially filled with a catalyst material or a materialthat is coated with catalyst material such that a flow channel remainsopen.

The term formed body refers to a conventional porous formed body, inparticular, a ceramic formed body, that has a porous support structureand is provided with a porous membrane layer on the side of theunfiltered fluid. Such known formed bodies are preferably also utilizedfor the filter element according to the invention, wherein the filterelement is, however, not limited to this type of formed bodies.

The standard material for the membrane layer consists of granularmullite. However, it would also be possible to utilize other materials.All ceramic oxides, nitrites and carbides are generally suitable forthis purpose.

The membrane layer may also consist of an asymmetric membrane layer thatis composed of several layers. The membrane layer thickness may amountup to 200 μm, wherein the pore size may lie between 0.05 and 40 μm. Themembrane layer is manufactured from bound inert grain or from fineparticles by means of polymer sol-gel methods. Spraying,electrophoresis, film casting, slip casting or the sol-gel method may beconsidered as coating methods.

The partial filling of the interior of the formed body with the catalystmaterial or with a material that is coated with catalyst materialprovides the advantage that identical-prefabricated formed bodies can beused for the manufacture of filter elements. These filter elements canbe adapted to the respective filtration task by selecting theappropriate catalyst material or filling. This makes it possible torealize a filter element kit such that a filter that fulfills thecorresponding requirements can be easily and rapidly produced and themanufacturing costs of the filter elements can be lowered.

The partial filling of the interior of the formed body such that adefined inner flow channel remains open has certain advantages incomparison to a completely filled interior. For example, a uniform flowof the fluid through the catalyst layer is ensured without risking thatbypass flows occur. If the formed body is completely filled, it is alsodisadvantageous that an uneven flow through the catalytically activebulk material can be expected in addition to bypass flows caused by themarginal flow conditions. This means that a controlled flow through thecatalyst material or the material coated with catalyst material isensured.

The filter elements may have different structural shapes. Consequently,the term filter elements refers to all structural shapes in which, forexample, the fluid to be filtered flows against the outer side of thefilter element and its walls form an interior space that is sealedrelative to the unfiltered fluid and open toward the filtrate chamber.In filter elements of this type, the flow direction of the fluid mayalso be reversed, but a filter element in which the fluid flows againstthe inner side is not equally well suited for all filtration tasks. Ofall possible structural shapes of filter elements, filter candles,filter cylinders and filter cassettes as they are described in greaterdetail below are particularly preferred.

The filter elements may be used for the filtration of gases, as well asfor the filtration of liquids. One preferred application consists of thefiltration of hot gases.

According to a first embodiment, a porous or perforated formed bodyinsert that causes the flow channel to remain open is inserted into theinterior of the formed body such that it is spaced apart from its wall.The intermediate space between the formed body and the formed bodyinsert is filled with a bulk catalyst material or a bulk material thatis coated with catalyst material.

The catalyst material is enclosed by the formed body and the formed bodyinsert such that the risk of loosening the catalyst material isminimized. The catalyst material or the material coated with catalystmaterial is preferably highly porous and uniformly arranged in theinterior with a constant layer thickness if the formed body insert isadapted to the shape of the formed body. This means that the samefiltration result is achieved at all points during the filtrationprocess. The term highly porous refers to a porosity greater than 60%.

The formed body insert preferably consists of a ceramic material, inparticular, of aluminum oxide, silicone carbide, titanium dioxide,silicone dioxide, zirconium oxide, calcium aluminate and/oraluminosilicates. It would also be conceivable to utilize mixtures ofthe aforementioned ceramic materials for the manufacture of the formedbody insert.

The formed body insert may also consist of a metal, e.g., special steel,Inconel or Hastelloy. Inconel® and Hastelloy® are trade names fornickel-based alloys that have special properties with respect to theirheat and corrosion resistance.

If the filter element is used at low temperatures, i.e., temperaturesthat lie significantly below 100° C., it is also possible to manufacturethe formed body insert of plastic. Preferred plastics that have acorrespondingly porous structure are polypropylene, polyethylene,polyolefins, polyamides, polysulfone and polycarbonate.

The formed body insert may also consist of a perforated formed bodyinsert. The term perforated formed body insert refers, for example, toscreen-type bodies.

According to another embodiment, a dimensionally stable catalyst body isinserted into the interior such that it adjoins the formed body, whereinthis catalyst body causes the flow channel to remain open and consistsof a catalyst material or a material that is coated with catalystmaterial. The catalyst body may, for example, consist of a catalystmaterial that is sintered together and has as a porous structureanalogous to the formed body such that fluid is also able to flowthrough the catalyst body. The partial filling of the interior of theformed body is realized in this embodiment by inserting a dimensionallystable catalyst body.

The uncoated material that is used in the form of a bulk material in thefirst-mentioned embodiment and in the form of a catalyst body in thesecond embodiment may consist of ceramic fibers or expanded ceramics, ofmetallic fibers or expanded metals and of plastic fibers or expandedplastics. The respective processing of these materials determineswhether they are used in the form of a bulk material or a dimensionallystable body.

The filter element may contain a cylindrical or rectangular formed bodywith an interior space that is closed on one side. This design refers toso-called filter candles and filter cassettes. Cylindrical formed bodiesare primarily utilized for filter candles and rectangular formed bodiesare primarily used for filter cassettes.

The formed body insert may consist of a tube that is open on one or bothsides. The term tube refers to a corresponding inner tube that, forexample, is inserted into a filter candle. The question whether thistube is open on one or both sides depends on the bottom wall of thefilter candle. If the bottom wall is permeable to the fluid, it ispreferred to utilize a tube that is open on both sides as the formedbody insert. If the bottom wall of the filter candle participates in thefiltration process, it is proposed to utilize a formed body insert inthe form of a tube that is closed on only one side and consequently alsocontains a bottom wall.

In a filter cassette that preferably contains a rectangular formed body,a correspondingly adapted formed body insert is used. This formed bodyinsert can also be referred to as a tube although the axial lengthshould be smaller than the diameter of the tube. In a rectangular formedbody, a correspondingly shaped rectangular tube is realized. Since thebottom wall is also utilized for the filtration process in filtercassettes, the formed body insert also contains a bottom wall. Thismeans that a tube which is closed on one side is used as the formed bodyinsert in this case.

The catalyst body that, according to the above-mentioned secondembodiment, is utilized in a filter element of this type also consistsof a tube that is open on one or both sides when it is used in acylindrical or rectangular formed body. The question whether a tube thatis open on one or both sides is used depends on the design of the bottomwall in case of a filter candle as described above. When used in filtercassettes, the catalyst body also contains a bottom wall.

The filter element may also consist of a filter cylinder that, inprinciple, consists of a cylindrical formed body with an interior thatis open on both sides. In this case, the formed body insert consists ofa tube that is open on both sides, wherein the tube is fixed in positionby corresponding cover elements arranged on the edge of the opening ofthe tube and of the formed body.

The catalyst body used in filter cylinders preferably also consists of atube that is open on both sides.

In all embodiments, the formed body inserts, as well as the catalystbodies, are realized in such a way that the entire filtration surfaceprovided by the filter body can be utilized.

According to another embodiment, the filter element contains adisk-shaped formed body with a peripheral wall, a bottom wall and a topwall which enclose a disk-shaped interior. In this case, an inlet oroutlet opening is respectively provided in the bottom wall and the topwall. As in the previously described embodiments, the formed body insertis realized in the form of a smaller version of the disk-shaped formedbody, namely such that the formed body insert encloses a flow channel.This also applies to a catalyst body used in such a disk-shaped formedbody. In order to introduce the formed body insert and the catalystmaterial or the material coated with catalyst material into thedisk-shaped formed body or to install the catalyst body, the formed bodyis preferably divided in the plane of the disk and consequently realizedin two parts.

The catalyst material consists of one or more oxides or mixed oxides ofrare earths and/or of one or more aluminates and/or of one or moresilicates and/or of one or more titanates or titanium dioxides.

The utilization of calcium aluminate is particularly preferred, whereinthe calcium aluminate may be used exclusively or in combination withother oxides or mixed oxides.

It proved to be advantageous that the catalyst material is modified withcatalyst promoters.

A particularly high effectiveness of the filter elements according tothe invention is achieved if the catalyst material is doped withcatalytically active precious or non-precious metals. Preferred dopingmaterials are platinum, palladium, rhodium, gold, silver, nickel,copper, manganese, vanadium, tungsten and/or cobalt.

Another advantage of the invention can be seen in the fact thatcatalytically active ceramic filter elements are obtained which areresistant to high temperatures, vapors and hetero-element compounds.This means that these filter elements can be directly arranged withinthe hot flue gas or exhaust gas flow while simultaneously ensuring thededusting of the hot gases, as well as the total conversion of organicpollutant components and residual components. In addition to the gascleaning effect, the basic substances for the formation of dioxins(DeNovo synthesis) are simultaneously filtered out.

The catalytic realization of the filter elements may include thebifunctional effect of the catalyst system, i.e., the total oxidationand the thermal-catalytic separation and consequently the reactionsdescribed below which depend on the respective catalyst material and, ifapplicable, the doping material used:

Catalytic reaction of nitrogen oxides, catalytic cracking of long-chainhydrocarbons, catalytic disintegration of organic compounds that easilyevaporate, total oxidation of carbon and carbon compounds, etc. However,the catalytic effect of the filter elements is not limited to theseparticular applications.

Exemplary embodiments of the invention are described in greater detailbelow with reference to the figures.

The figures show:

FIG. 1 the vertical section through a filter candle according to a firstembodiment;

FIG. 2 a horizontal section through a filter candle according to asecond embodiment;

FIG. 3 a vertical section through a filter candle according to a thirdembodiment;

FIG. 4 a vertical section through a filter candle according to a fourthembodiment;

FIG. 5 the vertical section through a filter cylinder according to afirst embodiment;

FIG. 6 a vertical section through a filter cylinder according to asecond embodiment;

FIG. 7 a perspective representation of a filter cassette;

FIG. 8 a vertical section through the first embodiment of the filtercassette shown in FIG. 7;

FIG. 9 a vertical section through a filter cassette according to asecond embodiment;

FIG. 10 a vertical section through a filter disk according to a firstembodiment, and

FIG. 11 a section through a filter disk according to a secondembodiment.

FIG. 1 shows a vertical section through a filter element 1 that isrealized in the form of a filter candle 2. The filter candle 2 comprisesa formed body 3 with a cylindrical peripheral wall 4 and a bottom wall5. A porous formed body insert 7 in the form of an inner tube 7′ isinserted into the cylindrical interior, wherein the formed body inserthas an outside diameter that is smaller than the inside diameter of theperipheral wall 4 such that an annular intermediate space remains whichis filled with a catalyst material 8. In order to prevent the catalystmaterial 8 from falling out, for example, when transporting the filterelement 1, a non-porous tight cover disk 6 with an inlet or outletopening 16 is fixed on the edge of the opening 15 of the filter element1, wherein said cover disk also fixes the inner tube 7 in its position.The inner tube 7 is inserted into an annular recess 17 in the bottomwall 5 and, for example, fixed therein by means of a putty or cement.The bottom wall 5 is not permeable to the unfiltered fluid.

Due to this arrangement, a partial filling of the interior of the formedbody 3 with catalyst material 8 is achieved, wherein said catalystmaterial has the uniform layer thickness over the entire periphery.

FIG. 1 also shows that the fluid flows against the filter element 1 fromthe radially outer side such that the space that surrounds the filterelement 1 forms the space 11 for unfiltered fluid. The cylindrical flowchannel 10 forms the filtrate space 12. The flow direction of thisfilter candle 2 may also be reversed as it is, for example, illustratedin FIG. 2. In this figure, the flow channel 10 forms the space for theunfiltered fluid and the space that surrounds the filter candle 2 formsthe filtrate space 12.

FIG. 2 shows a filter candle 2, the bottom wall 5′ of which consists ofthe same porous material as the peripheral wall 4 such that the bottomwall also participates in the filtration process. The formed body insert7 also consists of an inner tube 7″ in this embodiment, wherein theinner tube is, however, provided with a bottom wall 9. With respect toits shape and dimensions, the formed body insert 7 represents a smallerversion of the formed body 4. An intermediate space that is filled withcatalyst material 8 is also situated between the formed body insert 7and the formed body 3 in this case. In this particular embodiment,catalyst material 8 is also situated between the two bottom walls 5′ and9. The layer thickness of the catalyst material 8 is identical at alllocations in this embodiment such that the same filtration result isachieved in all effective filtration regions of the filter candle 2.

FIG. 3 shows another embodiment in which a dimensionally stable porouscatalyst body 14 that adjoins the formed body 3 is inserted into theinterior of the filter candle 2. The catalyst body has the shape of atube that is open on both sides. When utilizing a filter candle with theformed body according to FIG. 2, the catalyst body 14 also is providedwith a bottom wall. The end faces of the catalyst body 14 are fixed inthe formed body by means of a putty, for example, high-temperatureputty, or cement 13. Since the catalyst body 14 consists of a catalystmaterial or of a material coated with catalyst material, the interior ofthe formed body 3 also is partially filled with catalyst material inthis embodiment.

FIG. 4 shows another embodiment that merely differs from the embodimentshown in FIG. 1 due to the fact that the intermediate space between theformed body insert 7 and the formed body 3 is filled with a material 8′that is coated with catalyst material.

FIG. 5 shows an embodiment of a filter element 1 in the form of a filtercylinder 20. A filter cylinder 20 differs from a filter candle 2 due tothe fact that the filter cylinder, in principle, consists of a formedbody 3 in the form of a cylindrical tube that is open on both sides.This means that the formed body insert 7 is also realized in the form ofan inner tube 7′. In order to fix the catalyst material 8 in thecylindrical formed body 3, non-porous tight cover elements 6 areprovided. These cover elements respectively contain an opening 16 in theregion of the flow channel. The inner tube 7′ has the same length as theformed body 3.

FIG. 6 shows an embodiment of a filter cylinder 20, the design of whichcorresponds to the filter candle according to FIG. 3.

FIG. 7 shows a perspective representation of a filter cassette 30 thathas a rectangular outside contour. The cassette is provided with aperipheral flange 31 on the edge of the opening.

FIG. 8 shows a vertical section through the filter cassette 30 shown inFIG. 7 along the line A-A. The filter cassette 30 comprises a formedbody 3 that has the shape of a tube that is closed on one side. Thistubular formed body 3 may also be referred to as a cassette-shaped orpot-shaped formed body and has a peripheral wall 32 and a bottom wall33. The formed body insert 34 represents a smaller version of the formedbody 3 and consequently also has the shape of a tube that is closed onone side. This means that this formed body insert may also be referredto as a pot-shaped or cassette-shaped formed body insert. Catalystmaterial 8 is arranged in the intermediate space between the formed body3 and the formed body insert 34. A tight cover 6 that seals theintermediate space containing a catalyst material and fixes the formedbody insert 34 in its position is arranged on the flange.

FIG. 9 shows another embodiment that comprises a catalyst body 14′ thatis also realized in a cassette-shaped fashion and represents a smallvariation of the formed body 3.

FIG. 10 shows a filter element 1 that is realized in the form of ahollow filter disk 40 and contains a disk-shaped flow channel 10. Adisk-shaped formed body insert 45 that is fixed in its position by smallholding tubes 44 is inserted into the interior of this filter elementsuch that an intermediate space that is realized identically on allsides and filled with catalyst material 8 is formed between the formedbody 3 and the formed body insert 45. The two centrally arranged smallholding tubes a form inlet or outlet openings 46 depending on theoperating mode of the filter element.

FIG. 11 shows another embodiment with a catalyst body 14″ that is alsorealized in the shape of a disk. The hollow filter disk 40 has acircular shape and comprises bottom and top walls 42, 43, as well as acircular peripheral wall 41 with inlet or outlet openings 46, Thecatalyst body 1-4″ that is inserted into the disk-shaped interiorsurrounds the flow channel 10 and represents a small variation of theformed body 3 with respect to its shape and dimensions. A putty orcement is arranged in the inlet and outlet openings 46 in order to fixthe catalyst body 14″ in its position.

List of reference symbols

-   1 Filter element-   2 Filter candle-   3 Formed body-   4 Peripheral wall-   5, 5′ Bottom wall-   6 Non-porous tight cover-   7 Formed body insert-   7, 7″ Innertube-   8 Catalyst material-   8′Highly porous material coated with catalyst material-   9 Bottom wall of inner tube-   10 Flow channel-   11 Space for unfiltered fluid-   12 Filtrate space-   13 High-temperature putty or cement-   14, 14″ Dimensionally stable porous catalyst body-   15 Edge of opening-   16 Inlet or outlet opening-   20 Filter cylinder-   30 Filter cassette-   31 Flange-   32 Peripheral wall-   33 Bottom wall-   34 Formed body insert-   40 Hollow filter disk-   41 Side wall-   42 Bottom wall-   43 Top wall-   44 Small, non-porous tight tube-   45 Dimensionally stable porous catalyst body in the form of a hollow    disk-   46 Inlet/outlet opening

1. A filter element comprising a dimensionally stable porous formed bodywith an interior that forms a space for unfiltered fluid or a filtratespace, wherein the interior of the formed body includes a catalystmaterial or a material that is coated with catalyst material and an openflow channel.
 2. The filter element according to claim 1, wherein thedimensionally stable porous formed body has a wall, and furthercomprising a porous or perforated formed body insert which is insertedinto the interior such that it is spaced apart from the wall of thedimensionally stable porous formed body and causes the flow channel toremain open, and wherein the intermediate space between thedimensionally stable porous formed body and the formed body insert isfilled with the catalyst material or the material that is coated withcatalyst material.
 3. The filter element according to claim 2, whereinthe formed body insert comprises a ceramic material.
 4. The filterelement according to claim 2, wherein the formed body insert comprises ametal.
 5. The filter element according to claim 2, wherein the formedbody insert comprises a plastic.
 6. The filter element according toclaim 1, further comprising a dimensionally stable dimensionally stableporous catalyst body which is inserted into the interior of the formedbody, wherein said catalyst body comprises the catalyst material or thematerial that is coated with catalyst material and causes the flowchannel (10) to remain open.
 7. The filter element according to claim 1,wherein the uncoated material comprises ceramic fibers or expandedceramics.
 8. The filter element according to claim 1, wherein theuncoated material comprises metallic fibers or expanded metals.
 9. Thefilter element according to claim 1, wherein the uncoated materialcomprises plastic fibers or expanded plastics.
 10. The filter elementaccording to claim 2, wherein the dimensionally stable porous formedbody has a cylindrical or rectangular configuration and the interior isclosed on one side, and wherein the formed body insert comprises a tubethat is open on one or both sides.
 11. The filter element according toclaim 6, wherein the dimensionally stable porous formed body has acylindrical or rectangular configuration and the interior is closed onone side, and wherein the catalyst body comprises a tube that is open onone or both sides.
 12. The filter element according to claim 2, whereinthe dimensionally stable porous formed body has a cylindricalconfiguration and the interior is open on both sides, and wherein theformed body insert comprises a tube that is open on both sides.
 13. Thefilter element according to claim 6, wherein the dimensionally stableporous formed body has a cylindrical configuration and the interior isopen on both sides, and wherein the catalyst body comprises a tube thatis open on both sides.
 14. The filter element according to claim 2,wherein the dimensionally stable porous formed body has a disk-shapedconfiguration and includes a peripheral wall, a bottom wall and a topwall which enclose a disk-shaped interior, wherein an inlet or outletopening is respectively provided in the bottom wall and in the top wall,and wherein the formed body insert represents a smaller version of thedisk-shaped formed body.
 15. The filter element according to claim 6,wherein the dimensionally stable porous formed body has a disk-shapedconfiguration and includes a peripheral wall, a bottom wall and a topwall which enclose a disk-shaped interior, wherein an inlet or outletopening is respectively provided in the bottom wall and in the top wall,and wherein the catalyst body represents a smaller version of thedisk-shaped formed body.
 16. The filter element according to claim 1,wherein the catalyst material comprises one
 17. The filter elementaccording to claim 1, wherein the catalyst material comprises calciumaluminate.
 18. The filter element according to claim 1, wherein thecatalyst material is modified with catalyst promoters.
 19. The filterelement according to claim 18, wherein the catalyst material is dopedwith catalytically active precious metals or non-precious metals. 20.The filter element according to claim 19, wherein the catalyst materialis doped with platinum, palladium, rhodium, gold, silver, nickel,copper, manganese, vanadium, tungsten and/or cobalt.